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Apocynum cannabinum: anthocyanin content of stems and leaves

Lauren Guggina and Dana Dudle
Biology Department and Science Research Fellows Program, DePauw University
Summer 2006

Apocynum cannabinum is an herbaceous perennial native plant.  The stem and leaf color of A. cannabinum varies from green to dark red due to different levels of anthocyanin pigments. Anthocyanins have a variety of purposes for different plants, including photoprotection, osmotic balance, and protection of photolabile defensive compounds. In this study, we compared the anthocyanin content of stems and leaves of A. cannabinum in relation to light intensity.  We studied A. cannabinum in the Quarry Bottom where environmental conditions were stressful and the forested edge of a parking lot where conditions were less stressful. 

We designated plants as "sun" or "shade" according to visual observation of their surroundings. Irradiance was measured with a light meter at three hour intervals for three days. We collected stem and leaf samples, extracted anthocyanins, and assessed anthocyanin content using a spectrophotometer. 

Anthocyanin content was significantly higher in stems than leaves.  Anthocyanins were most concentrated in the vascular tissue of leaves.  Anthocyanin content differed significantly between stems in the sun and shade but not between leaves in the sun and shade. 

Investigating variation in anthocyanin content in A. cannabinum gives insight into what helps this plant survive in stressful conditions, such as the Quarry Bottom.  There are many environmental variables and stresses that A. cannabinum experiences in the Quarry Bottom. Anthocyanins may alleviate stresses associated with drought, rocky soil, and limited water availability.